1. Field of the Invention
The general inventive concept relates to a stage apparatus, and more particularly, to a stage apparatus having an improved structure to control a stage with precision.
2. Description of the Related Art
Generally, an ultra precision stage apparatus is used in a scanning device to inspect a semiconductor wafer or a liquid crystal display (LCD) that requires an ultra precision position control, a semiconductor processing apparatus and an ultra precision machining.
The stage apparatus includes a stage, such as a frame, to support a wafer of a semiconductor or the like, an actuator connected to the stage to move the stage, and a controller to control the actuator with precision.
U.S. Pat. No. 4,667,415, entitled Micro Lithograph Reticle Positioning System, discloses a conventional ultra precision stage apparatus. As shown in FIG. 1, the conventional stage apparatus includes outer frames 35 and 37 securely supported by a base, inner frames 41, 43, 45 and 47 of a rectangular shape provided inside the outer frames 35 and 37 and movable with respect to the outer frames 35 and 37, driving motors 61, 62 and 63 securely supported by a base or the like to push the inner frames 41, 43, 45 and 47, connecting rods 71, 72 and 73 to transmit driving forces of the driving motors 61, 62 and 63 to the inner frames 41, 43, 45 and 47 through corresponding holes 79, and a plurality of flexure hinges 51, 52, 53, 54, 55, 56, 57 and 58 provided between the inner frames 41, 43, 45 and 47 and the outer frames 35 and 37 to move the inner frames 41, 43, 45 and 47 on a plane in three degrees of freedom (X, Y, θ) due to the driving forces of the driving motors 61, 62 and 63.
The number of the driving motors 61, 62 and 63 is three, and the driving motors 61, 62, and 63 are provided outside a frame 33 of a rectangular shape. That is, the first driving motor 61 and the second driving motor 62 are provided outside the inner frames 41, 43, 45 and 47 and at right and left sides with respect to a center of a frame 31. The third driving motor 63 is provided outside the outer frame 37 and at the center of the outer frames 35 and 37. The first driving motor 61 and the second driving motor 62 drive the first connecting rod 71 and the connecting rod 72 to push the right and left sides of the inner frame 47, respectively. The third driving motor 63 drives the third connecting rod 73 to push the center of the inner frame 43. Here, the driving motors 61, 62 and 63 may be galvanometers.
The number of the connecting rods 71, 72 and 73 is three to correspond to the driving motors 61, 62 and 63. One side of each of the connecting rods 71, 72 and 73 is connected to a corresponding one of the driving motors 61, 62 and 63 by cranks 65, 66 and 67, and the other side of each of the connecting rods 71, 72 and 73 is connected to each of the inner frames 43 and 47.
With the configuration described above, a description of an operation of the conventional stage apparatus follows.
If the third driving motor 63 is driven, the inner frames 41, 43, 45 and 47 move along an X-axis, and if the first driving motor 61 and the second driving motor 62 are driven, the inner frames 41, 43, 45 and 47 move along a Y-axis. If the first driving motor 61 and the second driving motor 62 are driven in another way, each of the inner frames 41, 43, 45 and 47 rotates in clockwise and counterclockwise directions with respect to the center of the inner frames 41, 43, 45 and 47 in a θ direction.
However, in the conventional stage apparatus, the driving motors to produce a driving force are provided asymmetric, which causes a difficulty to reduce a position error if an ultra precision position control is required.
Further, in the conventional stage apparatus, the driving motors are used to move the frames, which have a difficulty in the ultra precision position control having a position error of tens of nm and may cause thermal deformations of the frames due to heat generated by driving the driving motors.